The PIE concept began simply as a description of innovative and responsive services; but it has rapidly gained momentum, to be seen increasingly as a desirable goal for services in homelessness.

Not unreasonably, however, commissioners and funders, and even senior managers within the sector, now wish to know what actual evidence there is that developing deliberately within the PIE framework will improve outcomes for this population.

There is also growing concern that some services may be describing themselves as PIEs, and some commissioners accepting that description, with little real understanding of what it entails, and how far the claim is justified, and no clear yardstick to measure or assess a service against.

Researchers, too, wishing to understand better the way the various identified elements in the framework each contribute and may work together to achieve whatever results they may do, would wish to see some clearer definitions of each of the key features, and also to assess how they work together to create a whole from the various parts.

The original formulation of a PIE – the customary, standard or "classic' framework (as outlined HERE ) - was intended to be both analytic and promotional; even inspirational. But whilst this may still hold good for such purposes, but it also has some blind spots, or awkward phrasing ( Discussed HERE ). The new and different task of assessment and specification may necessitate some small revisions of the now customary PIEs framework, in switching from identifying underlying thinking, to identifying observable practices.